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PO404 code help

9K views 15 replies 6 participants last post by  JMontgom 
#1 ·
I have been reading but I have not found anything that sounded like the same problem that I have.


I just got a 2004 chevrolet 2500 diesel and it has a 5 inch MBRP exhaust and a K&N airfilter nothing else. The PO404 code keeps coming on and I want it to stay off. What do I need to do?

Thanks, Matt
 
#3 ·
What is your location and do you have a CA emissions vehicle (sounds like you do) and do you have an LB7 engine?
 
#5 · (Edited)
It has nothing to do with the exhaust that is for sure. You might want to try to unplug the vacuum source to all of those solenoids above the fuel filter and see if the P0404 stays away after you clear the code. You will have to trace the vacuum line coming from the V pump and plug it. You'll probably get P0101 and P0401 but at least it will help diagnose the problem. These vacuumed EGR vehicles are a real pain.
 
#7 ·
If the valve is indeed stuck open and if you have emissions testing there then it needs to be replaced. I don't think its part of extended warranty however. Others hopefully will chime in here. If you don't have testing then I'd find someone with EFI live or better yet if you can afford it, buy it and just do away with the system. If the valve is stuck open, the cheapest way (using EFI live as well) would be to install a blocker plate and then disable the system with EFI live.
 
#9 ·
There are many vendors here that handle that stuff. Idaho Rob, SoCal Diesel, macrat to name a few. These guys are great to answer questions too.

PM sent.
 
#10 · (Edited)
I had the 0404 light forever, but after a couple of the solinoids got swapped out, I only get a 0401 light now! It is good to see a different code..................:rolleyes::mad:

EFI Live is the ONLY way to go, kinda pricey, but what would you pay for piece of mind?
If I could quit buying guns and ammo, I would be able to afford the EFI EASILY, but I guess you just have to prioritize.
 
#11 ·
Haven't they run out of ammo in FL yet Tolli? In northern Idaho they are getting it in again but for a while it was tough to get.
 
#12 ·
We are OUT!

But thanks to the internet, and occasionally I stumble across a couple boxes at Wally World....

Can you send me some?
 
#13 ·
MaxinDixon,

YOU Rock!!!!!!!!!!!!!!!!!!!!!!!!

Thanks for the hook up for the ammo, I feel much safer now.
 
#15 · (Edited)
Had mine reflashed, still have the occasional CEL..........
 
#16 ·
P0404 Help!!!!

Another P0404 question. I have a 03' CA Equipped LB7. Has a P0404 that will only clear for a few drive cycles, and then comes right back on.
Mods are 4" cat back, exhaust break and an AFE Stage II. All mods have been on this truck for 100k with no P0404 until now.
Have taken EGR off and inspected and tested good, so is vac pump, solenoid and vac lines.
Does anyone have any ideas???
Jason
 
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